If I were buying a new camera today, I would take a quick look at the OM5/EM1 and discard the notion based on not much weight or size savings compared to the D5200.

Totally different quality of bodies (magnesium ally vs plastic), control, viewfinder size, weather sealing, great IBIS, 9/10 fps sequential speed... If you don't need any of this, D5200 might be fine - of course it will be much heavier in your bag with lenses that E-M5 with lenses.